Answer:
it should be velocity and mass
If your findings disproves your hypothesis then your hypothesis is probably wrong.
Answer:
1.)
2.) 
3.) 2HCl
4.) MgO
5.) Mg and 
6.)
and 
7.)Na and 
8.) 3 aluminums and 3 chlorides
Explanation:
Ca(OH)2 (aq) because of elements oxygen and hydrogen